Co-pending co-owned U.S. Pat. No. 4,610,676 discloses an ostomy appliance coupling ring construction composed of a pair of relatively flat rings formed of polyethylene or other relatively soft, flexible plastic material. One of the rings has a tubular neck portion of limited axial extent terminating in an annular rim, the configuration defining a generally outwardly-facing channel that receives the annular collar or flange of the other ring when the two are coupled together. Contact between the two rings within the channel is responsible for producing an effective liquid-tight seal between the parts, and that seal is maintained despite the flexing and bending to which the rings are subjected in use because of a second zone of contact, well outboard from the sealing zone, that performs a primary latching function.
The basic purpose of the coupling ring assembly of the aforementioned patent, and of all other recent coupling ring assemblies for ostomy appliances, is to facilitate replacement of an ostomy pouch while at the same time permitting the adhesive faceplate to remain in position on the wearer's body. Thus, over a period of days, a number of pouches will be coupled to and uncoupled from a single faceplate coupling ring. Each time such coupling/uncoupling actions occur, there is a risk that the sealing surfaces of the rings might become scratched (as by a fingernail), nicked, or otherwise damaged. Any such damage, even a scratch too small to be readily observed by the naked eye, may be enough to provide a leakage pathway when the rings are joined together. The problem is compounded by the fact that such appliances are frequently worn by elderly or infirm patients who lack the minimal dexterity needed for easily coupling and uncoupling the rings and who may have difficulty manipulating such rings without damaging their sealing surfaces.
An important aspect of the present invention lies in the discovery that problems of leakage may be virtually eliminated, and other significant benefits may be obtained, if a viscoelastic polymeric liner is secured within the radially-facing channel of one of the rings. Particularly advantageous results are achieved if the viscoelastic liner, in addition to being deformable, also has controlled pressure-sensitive adhesive properties. Whether adhesive or not, the elastomeric liner deforms in response to unequal forces exerted by the flange of the other coupling ring when it is seated within the channel. Any voids between the two rings that might otherwise result in leakage or fluid bypass are effectively eliminated. The viscoelastic liner is also able to adjust itself to slight dimensional variations that may exist between successive pouch rings, thereby giving the user assurance that a single faceplate ring may be successively coupled to a multiplicity of pouch rings without risks of leakage.
Where the viscoelastic liner also has adhesive properties, it augments the security of attachment between the two rings as well as insuring against leakage. It is essential that the bond between the liner and the channel in which it is retained be greater than the adhesive attraction between the liner and the flange of the other ring so that, when the other ring is removed, the liner will remain within the channel. This may be achieved by forming the liner of a hot melt adhesive and then flowing that adhesive in a molten state into the channel where it solidifies or cures. Selective adherence of the liner to the channel-providing ring may also be controlled by selecting an appropriate formulation or surface treatment for the respective rings so that the surface of the other ring has less affinity for the adhesive than that of the channel-providing ring. Such treatments are well known in the art as disclosed, for example, in Park, W. R. R., Plastics Film Technology, pp. 154 et seq., (Van Nostrand Reinhold Company, 1969), and Satas, D., Handbook of Pressure Sensitive Adhesive Technology, 371 et seq., (Van Nostrand Reinhold Company, 1982).
Where the liner also has adhesive properties, it contributes in providing a coupling ring assembly that requires greater force to disassemble than to assemble. A user finds the rings may be easily slipped together into coupled relation. The substantially greater force required to separate them provides security against possibilities of unintentional separation of the parts.
Other features, advantages and objects of the invention will become apparent from the specification and drawings.